Diagnostic accuracy of non-invasive tear film break-up time assessed by the simple manual interferometric device

Abstract

<h2>Abstract</h2><h3>Aim</h3> To determine the diagnostic accuracy of non-invasive tear film break-up time (NIBUT) measured by the <i>handheld lipid layer examination instrument</i>. <h3>Methods</h3> 108 patients were enrolled in this cross-sectional study and divided into two groups: patients with dry eye (n = 57) categorized by the presence of dry eye symptoms obtained by Schein Questionnaire and minimally-one objective dry eye sign (tear film break-up time <10 s or corneal, conjunctival and lid margin fluorescein staining), and healthy subjects (n = 51). <h3>Results</h3> Dry eye subjects had significantly shorter NIBUT than healthy subjects (6 s vs 20 s, p < 0.001). Logistic regression analysis showed that shorter NIBUT values were excellent indicators of dry eye disease (p < 0.001), with consistency and no significant difference between measurements, even after standardizing the results for age and sex. NIBUT cut-off point to distinguish dry eye from healthy subjects was 12 s (sensitivity 90.2 %, specificity 88.5 %, PPV 92.5 %, NPV 85.2 %, LR +7.82, LR− 0.11, DOR 70.92, DE 89.6 %). Good, but lower accuracy was observed at cut-off value of 10 s (sensitivity 87.8 %, specificity 88.5 %, PPV 92.3 %, NPV 82.1 %, LR+ 7.61, LR− 0.14, DOR 55.2, DE 88.1 %). The area under the ROC curve (AUC) of 0.944 classified NIBUT as a diagnostic test with very high accuracy. <h3>Conclusion</h3> This study showed a high diagnostic accuracy of NIBUT measured by the handheld lipid layer examination instrument. This simple, reliable, objective and available instrument might regularly take place in routine, standard dry eye diagnostic and can be used by almost every eye specialist.